N = int(input())
c = list(str(input()))
r = c.count('R')
w = 0
for i in range(r):
    if c[i] == 'W':
        w += 1
print(w) N = int(input()) N int(input()) int input() input c = list(str(input())) c list(str(input())) list str(input()) str input() input r = c.count('R') r c.count('R') c.count c count 'R' w = 0 w 0 for i in range(r):
    if c[i] == 'W':
        w += 1 i range(r) range r if c[i] == 'W':
        w += 1 c[i] == 'W' c[i] c i 'W' w += 1 w 1 print(w) print w r = c.count('R') c.count('R') r w = 0 0 w N = int(input()) int(input()) N c = list(str(input())) list(str(input())) c w += 1 1 w
N = int(input())
c = list(str(input()))
r = c.count('R')
w = 0
for i in range(r):
    if c[i] == 'W':
        w += 1
print(w)